Many applications today require the navigation of a vehicle along a desired path. These applications vary widely and involve vehicles suited for travel over land, sea or air.
In many cases, the navigation of a vehicle is accomplished in one of three major ways. First, the function may be performed by a human being skilled in the operation of the particular vehicle. With an understanding of the vehicle performance characteristics and navigational control apparatus, the operator navigates the vehicle along the desired path. An example of this “manual” mode of navigation is the farmer steering his tractor across a field.
A second major navigational system features the use of one or more automated systems to assist a human operator in navigating/steering the vehicle. In many of these systems, which are referenced in this disclosure as “assistive” systems, the system evaluates the position of the vehicle compared to the desired path and provides feedback to the human operator usually by means of some kind of visual display.
A third major navigational system allows an automated system to take complete (or near-complete) control over the task of navigating the vehicle. An example of this type of “automated” mode of navigation is the “autopilot” which is commonly employed in modern jet aircraft.
Each of these navigational systems feature certain advantages and disadvantages. Manual systems, which rely upon human operators for most of the navigational control function, are inherently simpler and less expensive to own and operate. However, human operators have limitations which may affect efficiency. For example, a human operator may find it relatively easy to steer a twenty-four-inch-wide lawn mower across his lawn. However, if given the opportunity, that same operator would likely discover how difficult it is to efficiently navigate a ninety-foot-wide fertilizer sprayer across a thousand-acre field which is free of helpful landmarks. In attempting this latter task, he will discover that he frequently “skips” some large swaths of land (resulting in localized under-treatment of crops) while “overlapping” others (resulting in localized over-treatment of crops).
Assistive systems can dramatically improve the efficiency with which the operator navigates his vehicle. However, they can also be quite burdensome. Simply put, the farmer piloting today's complex, instrument-laden tractors has multiple duties; he cannot focus one hundred percent of his time and attention upon steering alone. Similarly, he finds it tiring to utilize assistive technologies that demand that he spend an entire ten-hour day staring at a feedback display.
For these reasons and more, there is a great demand for automated navigational systems. These systems, properly designed, have the potential for increasing the efficiency with which a vehicle is navigated while simultaneously freeing the operator to focus upon other tasks. Furthermore, use of automated technologies, such as the one described here, in agricultural applications can yield a significant reduction in fertilizer and herbicide spray overlap which results in benefits to the soil, crops, and waterways that receive run-off from treated land. Overlap reduction also results in the conservation of energy resources. It is to these automated systems, and to more user-friendly assistive systems, that this disclosure has primarily been directed.